1. Field of the Invention
This invention relates to personal watercraft and, more particularly, to watercraft that are portable and capable of being knocked down and erected easily with few or no tools required.
2. Description of Related Art
The present invention is a new type of collapsible kayak (a small paddle-powered watercraft with a covered deck). Using an innovative design system of structural folds in a semi-rigid plastic skin, it achieves unprecedented benefits in terms of performance, weight, portability, ease of assembly, aesthetics and manufacturing cost.
Kayaks, along with canoes and other lightweight, personal watercraft are commonly used for recreational travel on rivers, lakes and oceans. They are also used for fishing and hunting. Currently, commercial kayaks fall into three broad categories. The first and most common are rigid or “hardshell” kayaks. These are typically made of rotomolded or thermoformed plastics, fiberglass, or plywood. While such watercraft have excellent performance characteristics, their large size and weight makes them difficult and inconvenient to store and transport.
Due to these difficulties, there is a significant demand for watercraft that can be collapsed into small packages for storage or transport. The simplest of these are inflatable boats, which use a system of air-filled pneumatic tubes to provide form, structure and flotation. While such watercraft are compact and inexpensive, they are typically slow and hard to maneuver, due to shape limitations imposed by pneumatic systems.
Conventional collapsible kayaks are of a “skin on frame” construction system. That is, they are made up of a structural skeleton, which can be broken down into smaller pieces for storage and transport, and a waterproof fabric skin which fits over the skeleton. This system has the following disadvantages:                The structural skeleton is typically cumbersome and time-consuming to assemble, due to the large number of parts and connections.        The skin and structure are two independent systems, with the skin contributing nothing to the strength and rigidity of the kayak. As such, the weight of all of the components is generally too high for these kayaks to be carried on foot for any distance, limiting usefulness in many camping and traveling applications.        The skin fits loosely around the skeleton, increasing drag and decreasing performance, unless extra skin-tensioning elements—such as inflatable air tubes or mechanical jacks—are used.        The cost of such kayaks is prohibitively high for many consumers. This is due to the high cost of manufacturing a large number of relatively complex parts—both in the structure and the fabric skin, which must be manually sewn out of several pieces with waterproof seams.        
In recent years folding kayaks have been developed which, rather than a separate skin and structure, use systems of folding rigid panels. These address some of the problems of skin-on-frame systems, but until now, these have been outweighed by disadvantages:                Due to their folding geometries, such kayaks typically have an angular, boxy form which adversely affects stability, speed and overall performance in the water, as well as aesthetics.        Such rigid folding kayaks either only fold longitudinally—thus not decreasing the longest dimension for transport—or must be assembled from multiple pieces, which creates structurally weak and leak-prone seams.        